William Richards was the obvious suspect in the murder of his wife: Pamela was planning to leave him for another man, her killer did not rape her or steal anything, and Richards had no airtight alibi.
After three trials — the first two juries hung — Richards was finally convicted of murdering Pamela. A prosecution expert at the third trial — but not at the first two — testified that a crescent-shaped mark on Pamela's hand came from a bite that matched the unusual pattern of Richards' bottom teeth.
The dental expert later said he had been wrong, but the California Supreme Court decided 4-3 in 2012 to uphold Richards' conviction anyway.
"The case against petitioner was strong," retired Justice Joyce L. Kennard wrote for the majority back then.
On Thursday, the California Supreme Court changed its mind and decided unanimously to overturn Richards' conviction, citing a new state law that revised the legal meaning of "false evidence."
Now 66, Richards has served 23 years in prison for the crime. The California Innocence Project has spent nearly 20 years trying to free him.
"With the exception of the bite mark evidence, the defense had a substantial response to much of the prosecution's evidence against petitioner," wrote Chief Justice Tani Cantil-Sakauye, who had been part of the majority that upheld Richards' conviction.
She noted that all the evidence against Richards was circumstantial.
"Under these unique circumstances, it is reasonably probable that the false evidence presented … at petitioner's 1997 jury trial affected the outcome of that proceeding," the chief justice wrote.
Alarmed by the 2012 Richards decision, innocence projects and a class at the University of the Pacific's McGeorge School of Law helped persuade lawmakers to instruct courts that "false evidence" — grounds for a new trial — includes discredited forensic testimony.
The revision reflected the views of the three justices who dissented: Goodwin Liu, Kathryn Mickle Werdegar and Ming W. Chin.
Richards asked the state high court to reconsider his case in light of the new law. Forced to apply a different legal standard and analysis, the justices determined Richards' conviction could not stand.
Richards won his case a month after a parole board recommended he be released, a decision that is now before Gov. Jerry Brown.
Alex Simpson, a law professor and co-founder of the San Diego-based California Innocence Project, said he hopes San Bernardino County prosecutors will decide not to retry him and allow him to leave prison without the stain of a murder conviction.
The difference "between being paroled for murder and not having a murder conviction in the first place" is important, Simpson said.
He said investigators failed to find Pamela's true killer because they focused almost solely on her husband the night her body was found.
Christopher Lee, a spokesman for the San Bernardino County district attorney's office, said prosecutors were "reviewing the matter in order to determine the appropriate course of action.
Richards told sheriff's deputies that he discovered Pamela's body after returning home from work shortly before midnight on Aug. 10, 1993.
The couple had been married for more than 20 years and both openly had affairs with others. They lived in a camper in a remote setting in the high desert.
At the time of her death, Pamela, a waitress, was 40. Her husband was 43, a mechanical engineer. He had clocked out from work the night of the murder at a time that would have left him only minutes to strangle and bludgeon Pamela.
When investigators arrived, they found her body outside. She was naked from the waist down. Her head was crushed. One eye was left dangling. A blood-splattered cinder block sat next to her head.
Deputies could not find any footprints or tire tracks other than the couple's and those of the investigators, but the soil on much of the property was hard-packed and might not have shown prints.
The couple's dogs, usually hostile to strangers, had been roaming the property, leading police to believe that the animals knew the attacker. Investigators also found a paper written by Richards in Pamela's purse. The paper listed how their assets should be divided.
Although there was evidence of a struggle — Pamela broke a fingernail trying to defend herself and had several defensive wounds — there were no bruises or scratches on her husband.
A blood splatter expert testified that the bloodstains on William's clothing and shoes corroborated his statements that he had not killed Pamela but had cradled her head after finding her body.
Justices Liu and Carol A. Corrigan wrote dueling concurrences Thursday about the relevancy of the bite mark evidence.
Corrigan said it was impossible to say that the bite mark evidence caused the third jury to convict because there were many differences in the three trials.
Liu said the bite mark evidence had been critical.
"It was only at the final trial, where the false evidence was admitted, that a jury convicted Richards," Liu wrote.
Richards learned his conviction had been overturned Thursday, and "it was quite a shock," Simpson said.
"He has been trying to prove his innocence for more than 20 years," the lawyer said, "and he has now gotten to the point he can see the light at the end of the tunnel."